hg

histedit: add histedit.singletransaction config option

This adds an option (which defaults to False) to run entire histedits in a
single transaction. This results in 20-25% faster histedits in large repos where
transaction startup cost is expensive.

I didn't want to enable this by default because it has some unfortunate side
effects. For instance, if a pretxncommit hook throws midway through the
histedit, it will rollback the entire histedit and lose any progress the user
had made. Same if the user aborts editting a commit message. It's still worth
turning this on for large repos, but probably not for normal sized repos.

Long term, once we have inmemory merging, we could do the entire histedit in
memory, without a transaction, then we could selectively rollback just parts of
it in the event of an exception.

Tested it by running the tests with
`--extra-config-opt=histedit.singletransaction=True`. The only failure was
related to the hook rollback issue I mention above.

#!/usr/bin/env python
#
# mercurial - scalable distributed SCM
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import os
import sys

if os.environ.get('HGUNICODEPEDANTRY', False):
    try:
        reload(sys)
        sys.setdefaultencoding("undefined")
    except NameError:
        pass

libdir = '@LIBDIR@'

if libdir != '@' 'LIBDIR' '@':
    if not os.path.isabs(libdir):
        libdir = os.path.join(os.path.dirname(os.path.realpath(__file__)),
                              libdir)
        libdir = os.path.abspath(libdir)
    sys.path.insert(0, libdir)

# enable importing on demand to reduce startup time
try:
    if sys.version_info[0] < 3:
        from mercurial import demandimport; demandimport.enable()
except ImportError:
    sys.stderr.write("abort: couldn't find mercurial libraries in [%s]\n" %
                     ' '.join(sys.path))
    sys.stderr.write("(check your install and PYTHONPATH)\n")
    sys.exit(-1)

import mercurial.util
import mercurial.dispatch

for fp in (sys.stdin, sys.stdout, sys.stderr):
    mercurial.util.setbinary(fp)

mercurial.dispatch.run()